I voted for Usyk only for the reason that Bivoll was not fully tested (and neither was Usyk). If Bivoll was tested by a fight with Artur Beterbiev, and became the undisputed LHW champion, public opinion could change (also Usyk was not tested by Fury). Bivol has a chance to make a streak that boxing history would remember, especially because I don't think Dmitrii Bivol has shown us his peak yet.
Bivol was hyped like crazy when he came onto the scene. It's like people just forgot how good Bivol was for some reason. I don't think anyone who watched Bivol in 2017/2018 is surprised by anything that has happened this year.
Usyk. Similar level in terms of skillset - a smidge better, in fact. More angles from which he can deliver his...
Bivol because he gets hit less. Usyk is better tested though, he made world class fighters look clueless.